It should be underneath, pretty close to where you fill the fresh tank.
The Hot and Cold water drains you are talking about are the low point drains. After you drain the low points, you still have to do something. Either blow the lines out and/or run some antifreeze through them. DO NOT put antifreeze in the fresh tank! Not sure why people do that, I never saw a post telling to do that...
2016 Grey Wolf 26RR Limited
92 GMC K2500 454
2006 Honda Rubicon ATV